This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP third generation partnership project    Wi-Fi Wireless Fidelity, the wireless local area network (WLAN) technology based on the IEEE 802.11 standard. IEEE 802.11 covers technologies certified as IEEE 802.11a/b/g/n/ac/ad/af/s/i/v for example.    AP Wi-Fi access point    APN access point name    DHCP dynamic host configuration protocol    eNB evolved NodeB, base station in a LTE/LTE-A network    EPS evolved packet system    GTP general packet radio service tunnel    GTP-u GTP tunnel for user plane traffic    LTE Long Term Evolution, a technology standardized by 3GPP    LTE-A LTE-Advanced, a technology evolution step of LTE standardized by 3GPP    NAS non-access stratum    PDCP packet data convergence protocol    PDN GW packet data network gateway, a gateway in a mobile operator's network to service network connectivity of a UE    SDU service data unit    STA Wi-Fi station    TEID tunnel endpoint identifier of the GTP-u tunnel    UE user equipment, e.g., a cellular phone, smart phone, computing device such as a tablet    USIM universal subscriber identity module
Additional abbreviations that may appear in the description or drawings include:    ARQ automatic repeat request    DL downlink (eNB towards UE)    eNB E-UTRAN Node B (evolved Node B)    EPC evolved packet core    E-UTRAN evolved UTRAN (LTE)    GGSN gateway GPRS support node    GPRS general packet radio service    HARQ hybrid automatic repeat request    IMTA international mobile telecommunications association    ITU-R international telecommunication union-radiocommunication sector    MAC medium access control (layer 2, L2)    MM/MME mobility management/mobility management entity    OFDMA orthogonal frequency division multiple access    O&M operations and maintenance    PDCP packet data convergence protocol    PHY physical (layer 1, L1)    Rel release    RLC radio link control    RRC radio resource control    RRM radio resource management    SGSN serving GPRS support node    S-GW serving gateway    SC-FDMA single carrier, frequency division multiple access    UL uplink (UE towards eNB)    UPE user plane entity    UTRAN universal terrestrial radio access network
One modern communication system is known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). In this system the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300 V10.5.0 (2011-09) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 10) incorporated by reference herein in its entirety and referred to for simplicity hereafter as 3GPP TS 36.300.
FIG. 1A reproduces Figure 4.1 of 3GPP TS 36.300 and shows the overall architecture of the EUTRAN system (Rel-8). The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (u-Plane, PDCP/RLC/MAC/PHY) and control plane (c_Plane, RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to a S-GW by means of a S1 interface (MME/S-GW 4). The S1 interface supports a many-to-many relationship between MMEs/S-GWs/UPEs and eNBs.
The eNB hosts the following functions:
functions for RRM: RRC, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);
IP header compression and encryption of the user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards the EPC (MME/S-GW);
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
a measurement and measurement reporting configuration for mobility and scheduling.
Also of interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10) targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A).
Reference in this regard may be made to 3GPP TR 36.913 V10.0.0 (2011-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for further advancements for Evolved Universal Terrestrial Radio Access (E-UTRA) (LTE-Advanced)(Release 10). Reference can also be made to 3GPP TR 36.912 V10.0.0 (2011-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility study for Further Advancements for E-UTRA (LTE-Advanced) (Release 10).
A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LTE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8.
Section 4.3.1 of 3GPP TS 36.300, entitled User plane, shows in Figure 4.3.1-1: user-plane protocol stack (reproduced herein as FIG. 1B), the protocol stack for the user-plane, where PDCP, RLC and MAC sublayers (terminated in the eNB on the network side) perform the functions listed for the user plane in subclause 6, e.g. header compression, ciphering, scheduling, ARQ and HARQ. These protocols also serve the transport of the control plane.
Section 4.3.2 of 3GPP TS 36.300, entitled Control plane, shows in Figure 4.3.2-1 the control-plane protocol stack (reproduced herein as FIG. 1C), where the PDCP sublayer (terminated in the eNB on the network side) performs the functions listed for the control plane in subclause 6, e.g. ciphering and integrity protection. The RLC and MAC sublayers (terminated in the eNB on the network side) perform the same functions as for the user plane, the RRC (terminated in the eNB on the network side) performs the functions listed in subclause 7, e.g.: Broadcast; Paging; RRC connection management; RB (radio bearer) control; Mobility functions; and UE measurement reporting and control. The NAS control protocol (terminated in the MME on the network side) performs among other things: EPS bearer management; Authentication; ECM-IDLE mobility handling; Paging origination in ECM-IDLE; and Security control.
Also of interest herein is 3GPP TS 36.323 V10.1.0 (2011-03) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification (Release 10). FIG. 1D reproduces Figure 4.2.2.1 of 3GPP TS 36.323 and shows a functional view of the PDCP layer.
Also of interest herein is 3GPP TS 36.414 V10.1.0 (2011-06) Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 data transport (Release 10). FIG. 1E herein reproduces Figure 6.1: Transport network layer for data streams over S1 of 3GPP TS 36.414 and shows the transport protocol stacks over 51. The transport layer for data streams over S1 is an IP based Transport. The GTP-U (3GPP TS 29.281) protocol over UDP over IP is supported as the transport for data streams on the S1 interface. The transport bearer is identified by the GTP-U TEID (3GPP TS 29.281) and the IP address (source TEID, destination TEID, source IP address, destination IP address).
One benefit of offloading 3GPP LTE traffic to Wi-Fi is the availability of large amounts of license-exempt band frequencies for the traffic.
A problem that is encountered when considering offloading 3GPP LTE traffic to Wi-Fi is that LTE and Wi-Fi are completely different kinds of radios and, in addition, they use network connectivity protocols in different ways.
Even if Wi-Fi is used here to describe the Wireless Local Area Network, it may be possible to have another local area radio working in this type of a role. It is foreseen that 3GPP in the future may define an evolved local area radio technology that is compatible to the LTE/LTE-A radio interface but operates otherwise in a similar role as Wi-Fi.
This kind of an evolved local area radio may use a license-exempt frequency band, as in Wi-Fi, but it may as well be designed to use other bands, currently not available to cellular operators, such as spectrum bands that will become available via authorized shared access principles, cognitivity principles, flexible spectrum use principles and principles applicable to use of white spaces (e.g., unused spectrum between broadcast media bands), or any other new spectrum that becomes locally available. These kinds of opportunities for new spectrum for local use may actually make available large amounts of spectrum that would otherwise not be available for communications, and possibly for other purposes of spectrum use.